This invention relates to gripper mechanism for the head of a bolt. The gripper mechanism may be associated with various types of turning implements to impart turning motions to the bolt, e.g., socket wrenches, open-end wrenches, or box wrenches.
The gripper mechanism includes at least two angular cross section ribs adapted to interact with triangular grooves formed in side faces of the bolt head. The rib-groove interaction improves or enhances the grip action of an otherwise conventional wrench.
The triangular grooves may be formed in the bolt head during initial bolt manufacture. Conversely, the triangular grooves may be formed by the ribs during application of the wrench onto the bolt head. In the latter event, a hammering force is required to install the wrench onto the bolt. During the hammering period, the ribs penetrate the material of the bolt head; the bolt material is spread apart to form triangular grooves mated to side areas of the associated ribs. The mated surfaces absorb the wrench turning forces.
The invention seeks broadly to minimize wear or deformation of bolt heads by wrench turning forces. In the alternative, the invention seeks to form new thrust surfaces on already-worn bolt heads, thereby preserving or prolonging the bolt useful service life.